1. Field of the Invention
The present invention relates generally to pumps, motors, and the like using hydraulic or other fluid as a medium, and more specifically to various improvements in such a device having an angularly offset axis providing for simultaneous rotation and reciprocation of a positive displacement plunger. The improvements comprise various means providing for economy of manufacture, such as a split race for the spherical bearing incorporated therein and a negative draft casting for the seals thereof, as well as means providing for greater durability, such as a lubrication reservoir for the spherical bearing incorporated.
2. Description of the Prior Art
Positive displacement hydraulic pumps and motors using the principle of an angularly offset rotary axis to cause a piston or plunger to rotate and reciprocate simultaneously, have been known for some time. While development of such devices has continued, they nevertheless have various limitations relating to durability, reliability, cost, and ease of manufacture, particularly in such devices primarily adapted for smaller jobs and portability.
Generally in the past, the response to any such limitations has been to attack the problem from one end or the other, i. e., either the durability aspect or the cost aspect. Increases in durability have been achieved by using materials and components which are more difficult to machine and manufacture (e.g., stainless steels as opposed to softer metals and plastics), thus driving up costs, or to provide relatively inexpensive materials and manufacturing methods, thus reducing costs, but resulting in a decrease in durability and reliability. However, these two aspects are not necessarily completely mutually exclusive, as shown by the present fluid transfer device. A discussion of the limitations of the prior art, particularly in comparison with the present invention, is presented immediately below.
U.S. Pat. No. 1,147,116 issued to Budd G. Nice on Jul. 20, 1915 describes a Ball Bearing incorporating a diametrically split race. The race is not adaptable for use with a single spherical bearing, as it is not symmetrical, and even if machined for a spherical bearing, the wider portion could not be installed over the major diameter of the spherical bearing. The present invention provides for this with two symmetrical diametric spherical bearing race halves, which sandwich the single spherical bearing therein. A ball bearing configuration could not be applied to the device, as ball bearings require accurate axial alignment between rotating and fixed components at all times, whereas the angularly offset axis of the present device requires a spherical bearing to allow for the variation in alignment during each revolution.
U.S. Pat. No. 1,300,450 issued to Fred S. Morton on Apr. 15, 1919 describes a Ball Bearing having a diametrically and symmetrically split outer race, with a sleeve surrounding the two race halves to secure them together. However, Morton provides only a conical surface for his bearing race halves, as no use with other than plural ball bearings is anticipated. A plurality of smaller spherical ball bearings contained within an outer bearing race having conical surfaces, would provide only two contact points in the outer race for each ball. The present split bearing race or housing comprises a spherical concavity, closely fitting the corresponding single spherical bearing therein, and thus reducing the contact pressure at any given point. Further, the Morton bearing cannot tolerate misalignment, as provided by the present spherical bearing.
U.S. Pat. No. 1,312,962 issued to George J. Dourte on Aug. 12, 1919 describes a Valveless Pump providing double action, but the mechanism involves a crankshaft and bevel gear arrangement, in which an upper connecting rod is reciprocated by the crankshaft and rotated by the bevel gears. As the angle between the plunger rod and the connecting rod is continually changing, an additional pivotable connection must be provided between the two, as opposed to the fixed angular offset of the present fluid transfer device which allows the offset arm to be rigidly affixed to the plunger rod, thus providing a more durable mechanism. Moreover, Dourte does not provide additional volume in each end of his plunger, as provided by the present invention, for greater capacity.
U.S. Pat. No. 1,340,310 issued to George Wolff on May 18, 1920 describes an Antifriction Bearing comprising an axially split ball bearing race and cage, adapted for installation about a monolithic cylindrical crankshaft journal or the like. The spherical bearing housing of the present invention may be either axially split or diametrically split, but in either case, is adapted to fit closely about a single spherical bearing end to allow for the substantial axial misalignment between the shaft of the spherical bearing and the housing, as the alignment changes with each revolution of the angularly offset axis of the device. The axially split ball bearing race and cage of the Wolf patent cannot provide for any significant misalignment between the relatively stationary bearing block and rotating journal.
U.S. Pat. No. 1,927,466 issued to David B. Menton on Sep. 19, 1933 describes a Ball Bearing having a diametrically split outer race and a single piece inner race. While such construction provides complete enclosure for the plurality of bearing balls enclosed in the toroidal race therein, the single piece inner race cannot be separated for installation about a journal, as provided by other devices discussed above. In any case, the Menton bearing assembly is more closely related to those other devices with their plural bearing balls or spheres than to the present single spherical bearing, and cannot be adapted for use with the single spherical bearing of the present invention, or to allow for the cyclic axial alignment variation which occurs as a result of operation of the present device.
U.S. Pat. No. 1,967,821 issued to Donald P. Hess on Jul. 24, 1934 describes a Process Of Making Raceway Members for cylindrical or conically tapered roller bearings. The raceway members are formed by making rings of flat stock, and welding the ends of each ring together to make a closed raceway. The resulting closed cylindrical form is then processed and machined conventionally to form a conventional, closed bearing race. While various alternative configurations are disclosed for the blanks, they are all welded closed in the manufacturing process. Hess does not disclose any finished bearing races which are split in any way, as provided by one of the features of the present invention.
U.S. Pat. No. 3,168,872 issued to Harry E. Pinkerton on Feb. 9, 1965 describes a Positive Displacement Piston Pump in which at least one embodiment, functions similarly to the present fluid transfer device. However, numerous differences are noted. The piston or plunger of the Pinkerton pump is externally slotted, rather than having internal passages as in the present invention. While double action is provided, such is only possible using a double cylinder with the plunger having two working ends. Also, the spherical connector between the pump drive motor and the angularly offset plunger rod is installed through the wall of a cup-like component; no sealing of any lubricant around the spherical bearing is provided, nor is any means for lubricating the fitting disclosed. Further, any fluid leakage past the end of the cylinder is free to flow to the external environment, and no sealing means between plunger or rod and cylinder bore is disclosed.
U.S. Pat. No. 3,266,432 issued to Stewart W. Wortley on Aug. 16, 1966 describes a Pump having a single cylinder with a piston centrally located therein. A valve is positioned on each side of the piston, with each valve alternatingly covering and uncovering an intake and a discharge port. Reciprocation of the piston is accomplished by an angularly adjustable swash plate, rather than an angularly offset arm, as in the present invention. The device is equivalent to a two cylinder pump, with the single piston alternatingly reciprocating through the central bore of the single cylinder in each direction. While the Wortley pump is double acting, it requires the equivalent action of two cylinders in order to function in such a manner, and the complexity of separate valves which rotate and reciprocate with the piston and rod.
U.S. Pat. No. 3,447,468 issued to Walter E. Kinne on Jun. 3, 1969 describes a Metering Pump which functions somewhat along the lines of the device of the patent to Wortley discussed immediately above. Kinne, however, provides an elongated and slotted piston or plunger which also acts as a valve means as well as separating the two ends of the cylinder. A pressurized fluid is applied to one end of the cylinder through radially disposed ports, which provides reciprocation of the piston as it rotates, thereby causing a pumping action of fluid through the opposite end of the cylinder. Rather than using fluid means to reciprocate the plunger, the present invention utilizes mechanical means with an angularly offset arm.
U.S. Pat. No. 3,597,819 issued to Hudson B. Scheifele on Aug. 10, 1971 describes a Method Of Making A Composite Tapered Roller Bearing Race. The method is similar to that disclosed in the patent to Hess, discussed further above, in that two pieces of straight bar stock are rolled to form two semicircles and the ends welded together and smoothly finished to form a cylindrical bearing race. Scheifele provides only completely circular races, and does not disclose the use of split races (either diametrically or axially) in a completed bearing. In any case, the stock used by Scheifele would require further machining, in order to be compatible with a single spherical bearing as used in the present invention.
U.S. Pat. No. 4,008,003 issued to Harry E. Pinkerton on Feb. 15, 1977 describes a Valveless Positive Displacement Pump similar to that disclosed in his earlier '872 patent. However, Pinkerton recognizes the desirability of providing equal volumes at each end of the cylinder for any given respective positioning of the piston or plunger therein, and provides an idler rod which extends through the opposite end of the cylinder from the drive rod in order to displace a volume equal to that of the drive rod. This results in further complexity, in that additional sealing around the idler rod is required. While the volumes at each end of the double acting plunger of the present invention may not be precisely equal due to the single rod extending from one end of the plunger, the sealing of the present apparatus is considerably more reliable than the multiple seals required of the Pinkerton device.
U.S. Pat. No. 4,067,668 issued to Erik A. Nimell on Jan. 10, 1978 describes a Valveless Rotary-Oscillating Double-Acting Piston Pump. The pump comprises a cylinder with opposite closed ends having oblique internal surfaces, and a plunger installed therein with complementary oblique end surfaces and opposite passages communicating with opposed side ports in the cylinder. As the plunger is rotated, the ends ride against the oblique internal ends of the cylinder to force the plunger to reciprocate simultaneously, thereby alternatingly changing the volume at each end and producing a double acting pumping action. While the device is exceedingly simple, it nevertheless relies upon an internal axially sliding coupling between the motor shaft and the plunger, as well as the sliding of the plunger within the cylinder bore. The relatively small diameter rod seal and spherical bearing of the present device appear to provide lower friction and better sealing.
U.S. Pat. No. 4,941,809 issued to Harry E. Pinkerton on Jul. 17, 1990 describes a Valveless Positive Displacement Metering Pump. the device is similar to those disclosed in the same patentee's earlier '872 and '003 patents, but includes an angularly adjustable table to adjust the angular offset between the drive motor and the pump cylinder and plunger. Reversibility is provided by swinging the cylinder and plunger axis from one offset side to the other, thereby reversing the intake and outlet ports of the cylinder when the plunger is respectively in compression and expansion strokes. In any case, the same distinctions between this device and the present invention apply, as discussed further above.
U.S. Pat. No. 5,074,767 issued to C. Richard Gerlach et al. on Dec. 24, 1991 describes a Positive Displacement Pump With Rotating Reciprocating Piston And Improved Lubrication Feature. The single plunger has a single, central bore which communicates with a single lateral passage in the plunger. An inlet and an opposite outlet port are disclosed, but due to the single passage and central bore, the Gerlach et al. device is only single acting, and has no double action. Thus, when fluid is being expelled from the outlet port, no fluid is flowing into the inlet port, and vice versa. The present device provides for simultaneous inlet and outlet flow, due to the separate inlet and outlet passages and sides of the single plunger. Also, while Gerlach et al. disclose a lubrication pocket for the bearing, no means is provided to add grease to the pocket, without disassembly of the pump.
U.S. Pat. No. 5,246,354 issued to Guillermo P. Pardinas on Sep. 21, 1993 describes a Valveless Metering Pump With Reciprocating, Rotating Piston. The cylinder includes a single inlet port and two outlet ports, with the three ports being radially spaced apart about the cylinder. The single plunger includes a single relief on one side, which alternatingly communicates with the ports. The advantage of the Pardinas device is that the timing between the relief and the ports may be adjusted to provide accurate metering of fluid from the pump. However, the single relief of the plunger provides only a single acting pump, with the inlet function being idle when fluid is passing through the outlet port(s), and vice versa.
Finally, U.S. Pat. No. 5,287,623 issued to Thomas M. Francis et al. on Feb. 22, 1994 describes a Bearing Split Outer Ring And Method Of Assembly. The disclosure is directed to an axially split housing or race for use with plural individual bearing units (balls, rollers, etc.) and cannot be adapted to a single spherical bearing, as the outer race or housing is specifically divided axially into two unequal parts. The larger of the two components subtends an arc of greater than 180 degrees, and thus cannot be fit around a single spherical bearing. The problem is similar to that of the '116 patent to Nice discussed initially, in that asymmetrical bearing shells are disclosed in both patents. Nice, however, uses a diametrically split shell, whereas Francis et al. uses an axially split shell. Neither is adaptable for use with a single spherical bearing, as noted above.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.